KIEV, May 3 - European military observers held captive in Slaviansk in eastern Ukraine were released on Saturday, the town's pro-Russian separatist leader said, characterizing the move as voluntary and made to coincide with his birthday, Reuters reported.

"As I promised them, we celebrated my birthday yesterday and they left. As I said, they were my guests," Vyacheslav Ponomaryov said, adding that 12 people had been freed, including Europeans and Ukrainians.